Can seam forming apparatus

ABSTRACT

A double seam forming apparatus for applying end units to can bodies includes a can seamer ( 12 ) with a seaming cam ( 46 ). Seaming cam ( 46 ) includes a high dwell portion ( 56 ) which deforms responsive to force encounterred by tooling during forming of a can seam. A reinforcing pin ( 72 ) limits deformation of the high dwell portion to prevent damage. The high dwell portion of the cam includes a force sensor ( 20 ) which generates a signal responsive to strain of the high dwell portion due to applied force. The apparatus further includes a monitor apparatus ( 28 ). The monitor apparatus includes a controller ( 30 ) which includes a processor and a data store ( 32 ), and a host station ( 38 ). The monitor apparatus is operative to identify seam fault conditions and to store data concerning seamer conditions. The monitor apparatus also operates a can ejector ( 26 ) to divert cans identified as having defective seams.

This application claims the benefit of provisional application Ser. No.60/023,673 filed Aug. 21, 1996.

TECHNICAL FIELD

This invention relates to can closing machines. Specifically thisinvention relates to a double seam forming can closing apparatus whichidentifies defects and rejects cans with improper seams. This inventionfurther relates to a double seam forming can closing apparatus in whichthe seam forming parameters may be set up more rapidly and reliably.

BACKGROUND ART

Canning equipment and processes are commonly used in a variety ofindustries. Canning processes are often used to preserve food productsbecause such products can be processed and promptly hermetically sealedwithin a can. Canning operations may be performed at high speed and at areasonable cost. The sealing of cans is important because an improperseal may result in the infiltration of air to the interior of the can.This may result in bacterial growth and premature spoilage.

Can closing machines are known in the prior art. One type of can closingmachine secures an end to a can body after the product has been placedin the can by formation of a folded double seam. An example of a doubleseam forming machine which secures top ends to can bodies is shown inU.S. Pat. No. 3,465,703. The disclosure of this Patent is incorporatedherein by reference.

The goal of a double seam forming machine is to produce a perfect seamwhich extends about the circumference of every can that passes throughthe machine. Unfortunately this is not always possible. Undesirableconditions may occur due to defects in either the can body or the canend. Such defects may include undesirable variances in dimensions inwhich the ends do not perfectly “fit” the can bodies. Variations inmetal thicknesses may also occur which impacts the ability to form aproper double seam.

Other conditions which may cause imperfect seams include cracks or tearsin the can bodies or can ends. Such defects may result in loose or openspaces in the seam. Similarly, defective manufacture of the ends orbodies may result in folds or areas having excessive metal thickness.Such defects in the area of the seam also prevent proper seam formation.

Defects in the chucks or rolls which are used to form the seams can alsoresult in defective can seams. Such defects may include the accumulationof metal on a chuck or roll. The accumulated material causesirregularity in the tooling surface in contact with a seam as it isbeing formed and can result in an improper seam. Alternativelythe-chucks or rolls used to form the seam may crack, producing a gap.The seam is not properly formed in the area of the gap which results inimproper can closure.

Double seam can closing machines generally include several stationswhere cans are formed. They include multiple associated sets of chucksand rolls which perform the same operations. If a tooling problem occursat one chuck or roll, it will not be readily apparent because only cansthat have been acted upon by the defective tooling will exhibit animproper seam. Double seam forming machines typically operate at veryhigh production rates. It is therefore difficult to detect a problem assoon as it occurs. Hundreds or thousands of cans that are potentiallydefective could be closed before a problem is noticed.

In an effort to improve the inspection of can seams produced by a doubleseam can closing machine, others have developed devices to monitor seamquality. An example of such a device is shown in U.S. Pat. No.4,600,347, the disclosure of which is incorporated herein by reference.This Patent discloses a modification to a standard can closing machinein which force sensors are installed on a stationary cam. Cam followersmove around the stationary cam in engaged relation therewith. The camfollowers are in connection with the rolls which contact the can endsand chucks which form double seams. The contour of the cam moves the camfollowers, which in turn move the rolls to form the seams.

In the prior art device the sensors on the stationary cam detect theforce applied by the cam followers during the final ironing turn of thecan seam before the can leaves the machine. The force applied to thestationary cam by each cam follower during this operation corresponds tothe configuration of the formed can seam about its circumference. Theprior art device works on the principle that by monitoring the forceapplied by the cam follower for each station as it performs the finalironing turn on the seam, certain defects can be identified. Commondefects include situations where the seam is either too tight or tooloose. Such defects may arise in the form of a consistently high or lowforce or a transient force “spike”. A high transient force spikeindicates excessive metal on either the can seam, forming roll or atooling chuck. Alternatively, a transient low spike may be indicative ofa cracked tooling roll or chuck, or a gap or tear in a can seam.

While the device shown in U.S. Pat. No. 4,600,347 represents asignificant advance in the detection of seaming problems, it suffersfrom several drawbacks. These drawbacks include the fact that doubleseam forming can closing machines generally include many stations. Thetooling associated with each can closing station is somewhat different.This results in variation of the force that is applied by each camfollower as it moves across the force-sensing portion of the stationarycam. As a result, the amount of force associated with a “good” seam indifferent stations can vary significantly. The prior art devices cannotaccount for this variation in normal loading between the various machinestations. Rather, the prior art generally compares the applied seamforce to a single high limit or low limit for all the stations. Theselimits must have a range that accommodates the force at all machinestations. An improper fault indication may result if the limits are settoo narrowly. However, if the limits are set too widely then defectivecans may be allowed to pass.

A further drawback associated with the prior art is that forcevariations that result from excess metal or a broken seam or chuck, areonly detected if the corresponding spike is sufficiently “high” or “low”to extend beyond the limits which are established for a tight or a looseseam. Spikes or breaks that occur within the limits may be indicative ofa developing tooling problem and/or have adverse consequences for theseam. However, in the prior art such conditions may go undetected.

A further drawback associated with the prior art is that developingproblems with tooling, can bodies and can ends often go undetected untilone of the limits is exceeded. Dimensional changes in the seam may beginmoving the seam tolerances toward a limit. Such movement of seamconditions away from the optimum, increases the risk of seam failure. Itmay be advisable to correct such problems before they result in a faultcondition. Unfortunately because the prior art devices cannot accountfor variations from station to station, such trends are difficult todetect.

Can seamers usually run at high speeds. As a result if a single canexhibits a fault condition, it is necessary to either shut the machinedown or to locate the defective can among a large population of goodcans. Stopping the machine delays production which increases costs andrequires a set-up person's attention for restart. Alternatively, notshutting the machine down while attempting to locate the can that isdefective may be very time consuming. Visual inspection often may notreadily distinguish a defective can which further complicates theproblem.

A further drawback associated with the prior art systems is that theymay be subject to false triggering. Vibration or other conditions mayresult in short-term “noise” from the sensors on the stationary cam.This noise may produce a signal which falls outside the high and lowlimits, which causes a fault indication to be given. Considerable effortmay then be expended in an effort to locate a problem that does notexist.

A further drawback associated with such prior art systems is the timenecessary to set up the system. Generally such set-up requires theobservation of sensor output signals produced by a number of cans withgood seams. These seam “profiles” must be observed and documented foreach of the several stations of the machine. This task is complicated bythe fact that sensor signals for a good seam can vary from station tostation as previously discussed. Once the various seam profiles andforce levels have been studied for a number of good cans passing througheach of the stations, it is then necessary to set the high and low limitvalues at levels sufficient to accommodate the variation in forceapplied by the cam followers for numerous seams. The high and low limitsmust be set far enough apart so that frequent false indications are notgiven. This process of observing seam profiles for numerous documentedgood seams at each of the numerous stations on the double seam formingmachine is time consuming.

A further drawback associated with the prior art systems is that theinstrumented portion of the cam is ideally relatively flexible comparedto other portions of the cam. This is done for example as shown in U.S.Pat. No. 4,600,347 by providing a slit which extends radially betweenthe instrumented portion of the cam and the main portion of the cambody. This enables the instrumented portion to more readily deform. Anindication of the applied force is obtained using strain gage typesensors.

Making the instrumented portion of the cam more flexible also reducesits strength. There is a risk that the instrumented cam portion mayfracture or take on a permanent set due to the application of excessiveforce. Such excessive force may result from a situation where additionalmetal is present on a can, roll or chuck. Damage to the cam generallynecessitates cam replacement. This is costly and time consuming. Furthercosts may be associated with production downtime.

Thus there exists a need for a double seam forming apparatus whichovercomes the drawbacks associated with prior art systems and which isreliable and economical.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a double seamforming apparatus for applying end units to can bodies.

It is a further object of the present invention to provide a double seamforming apparatus which identifies defective can seams.

It is a further object of the present invention to provide a double seamforming apparatus that identifies particular fault conditions of aformed seam.

It is a further object of the present invention to provide a double seamforming apparatus that minimizes the risk of false fault indications.

It is a further object of the present invention to provide a double seamforming apparatus that monitors seam conditions and accounts forvariations in tooling at the stations of a multi-station machine.

It is a further object of the present invention to provide a double seamforming apparatus that identifies seam imperfections even when suchimperfections do not place the seam parameters outside of acceptablelimits.

It is a further object of the present invention to provide a double seamforming apparatus that can be used to identify trends in seamcharacteristics.

It is a further object of the present invention to provide a double seamforming apparatus that can reject cans with defective seams withouthaving to stop the operation of the apparatus.

It is a further object of the present invention to provide a double seamforming apparatus that has reduced set-up time compared to priordevices.

It is a further object of the present invention to provide a double seamforming apparatus that reduces the risk of cam failure.

It is a further object of the present invention to provide a double seamforming apparatus that is reliable and economical to operate.

Further objects of the present invention will be made apparent in thefollowing Best Modes For Carrying Out Invention and the appended claims.

The foregoing objects are accomplished and a preferred embodiment of theinvention by a double seam forming apparatus that secures and seals endunits to can bodies through the formation of a double seam. These endunits are generally top ends which are applied after a product has beenplaced in the can. Alternatively the present invention may be used inconnection with the application of bottom ends which are seamed prior toplacing product in the can.

The apparatus includes a cam with at least one seaming track. Theseaming track includes a high dwell portion. Cam followers in operativeconnection with seam forming rolls and chucks engage the high dwellportion as cans undergo a final ironing turn to form the double seam.

A sensor is mounted in operative connection with the high dwell portionof the seaming track of the cam. The sensor operates to generate signalsresponsive to the force applied by cam followers which cause slightdeformation of the cam as they move across the high dwell portion. Theforce applied by each cam follower on the high dwell portion isrepresentative of the force applied by the cam forming roll and chuck tothe circumferential can seam that is formed while in engaged relationtherewith.

The apparatus of the preferred form of the present invention includes acam body which is relatively rigid compared to the instrumented portionof the cam. An extending portion of the cam body engages the high dwellportion with the cam body responsive to the high dwell portionapproaching its maximum permissible deflection. This might occur in afault situation. The extending portion provides reinforcement andreduces the risk of the high dwell portion permanently deforming orfracturing.

The apparatus of the invention includes a monitoring apparatus orsystem. The monitoring system is in operative connection with thesensor. The monitoring system has a sampling portion that operates tosample sensor signals at a plurality of locations as the cam followermoves across the high dwell portion of the cam. This is done for the camfollower associated with each station as each can seam undergoes itsfinal ironing turn.

The monitor system further includes a data generating portion which isoperative to produce a plurality of data elements representative of acan seam profile. In a preferred form of the invention the data elementsare generated by a base line reference generating portion included inthe data generating portion. The base line reference generating portionsubtracts from each sensed value a corresponding value in a base lineprofile, which base line profile is established and stored in a memoryduring set-up of the system. In the preferred embodiment, a can whichhas a seam which does not vary significantly from the base line profileproduces a can seam profile that is represented by a generally straightline and which does not deviate significantly from the base lineprofile.

The monitoring system of the apparatus in the preferred embodiment alsohas an averaging portion that operates to average all the data elementsthat are calculated for each can seam. This average is compared to aplurality of stored threshold values. In a preferred embodiment thisaverage is compared to threshold values stored in a limit storageportion of the monitor system, which stored values correspond to a tightfault condition, a tight warning condition, a loose fault condition anda loose warning condition. Can seam data for each can is stored in adatabase along with an indication of any threshold values that arecrossed. Crossing threshold values for fault conditions causes a signalgenerating portion of the monitoring system to set a flag associatedwith the can identified as having a defective seam.

The monitoring system further includes a comparator portion which isoperable to compare each of the data elements for the particular seam tothe average of all the data elements for that seam. Variation of aparticular data element above the average by more than a high setthreshold amount may be indicative of high transient force associatedwith excess metal on a chuck, roll, or seam. Likewise, variation of adata element from the average below a set low threshold amount may beindicative of a broken seam, roll or chuck. If such a high or lowvariation from average is encountered a discriminating portion of themonitoring system operates to compare a number of adjacent data elementsin the seam profile to verify that such condition existed for asufficient time so as to be representative of an excess metal or brokencondition rather than a transient noise signal. Upon identifying a metalor broken condition the signal generating portion the monitor system ofthe apparatus flags the can as having a defective condition.

The preferred embodiment of the invention further includes a feed sensorfor sensing when cans are delivered to a station of the apparatus. If nocan is delivered to a station a disregarding portion of the monitoringsystem is operative to disregard sensor readings from that station whenits associated cam follower passes over the instrumented cam portion.

The preferred form of the invention also includes a reject portion whichis operative to divert cans that have been flagged because they exhibita fault condition. The reject portion is operative to divert such cansafter they have passed through the machine so as to segregate defectivecans from good cans without having to shut down the apparatus.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a seam forming apparatus of the presentinvention.

FIG. 2 is a top plan view of a stationary seaming cam of the seamforming apparatus.

FIG. 3 is a cross-sectional view of the seaming cam along line 3-3 inFIG. 2.

FIG. 4 is a view of an inner surface and notch of the seaming cam alongarrow 4 in FIG. 3.

FIG. 5 is a cross-sectional view of the seaming cam taken along line 5—5in FIG. 3 with a cam follower shown in engaged relation therewith.

FIG. 6 is a screen display of a host station of the present inventionindicating threshold value limits that have been set up for seamparameters which are monitored during operation of the apparatus.

FIGS. 7 through 10 are a flow chart of process steps executed by aprocessor in an embodiment of the apparatus.

FIG. 11 is a cross-sectional view of a normal double seam produced bythe apparatus of the present invention.

FIG. 12 is a screen display of the host station showing an outputrepresentative of a seam force profile corresponding to the normal seamshown in FIG. 11.

FIG. 13 is a cross-sectional view of a tight seam.

FIG. 14 is a screen display of the host station corresponding to thetight seam shown in FIG. 13.

FIG. 15 is a cross-sectional view of a loose seam.

FIG. 16 is a screen display of the host station corresponding to theloose seam shown in FIG. 15.

FIG. 17 is an isometric view of a can seam forming chuck includingexcess metal build-up on a portion of its working surface.

FIG. 18 is a screen display of the host station corresponding to a seamformed using the chuck with metal build-up shown in FIG. 17.

FIG. 19 is an isometric view of a seam forming chuck having a break orgap in its working surface.

FIG. 20 is a screen display of the host station corresponding to a seamformed with the broken chuck shown in FIG. 19.

FIG. 21 is a view of a screen display of the host station showing seamprofiles produced by all the stations of a six station seam formingembodiment of the invention.

FIG. 22 is a schematic view of a reject portion of the apparatus usedfor diverting defective cans.

FIG. 23 is a view of a display of the host station showing the seamqueue and the reject queue of the apparatus of the present invention.

FIG. 24 is a screen display of the host station showing seam history forthe six station embodiment.

FIG. 25 is a view of a screen display of the host station disclosingtotals for seam data at each station of the six station embodiment.

FIG. 26 is a view of a screen display of the host station showing a logof messages in the monitoring system portion of the apparatus.

FIG. 27 is a flow chart of process steps executed by a processor of themonitoring system portion of the apparatus for developing a base lineprofile for a can seamer station.

BEST MODES FOR CARRYING OUT INVENTION

Referring now to the drawings and particularly to FIG. 1, there is showntherein a schematic view of an embodiment of the apparatus of thepresent invention generally indicated 10. The apparatus includes adouble seam forming can seamer 12. In the preferred form of theinvention seamer 12 is of the type that attaches can ends on to canbodies through formation of a hermetic folded double seam. The seamermay be of a type shown in U.S. Pat. No. 3,465,703 which performs firstand second seaming operations to form a circumferential seam. The seamerpreferably includes a plurality of stations. For purposes of thisillustrative embodiment the seamer includes six (6) stations. Of course,seamers with different numbers of stations may alternatively be used.

The apparatus 10 is in operative connection with a feed conveyor 14.Feed conveyor 14 feeds open can bodies preferably containing a productto seamer 12. A take-away conveyer 16 carries away the cans upon whichthe ends have been installed.

An encoder schematically indicated 18 is in operative connection withthe seamer. In the preferred form of the invention, encoder 18 is anoptical encoder which is in connection with a timing shaft of theseamer. The optical encoder in the preferred form of the invention usedwith the six station seamer provides 2,400 evenly spaced pulses perrotation of the timing shaft. The encoder also provides aninitialization pulse during each rotation in accordance withconventional encoder operation. The signals from the encoder 18 enablethe positions of the components of the seamer to be derived at any pointin the machine cycle. Of course other types of encoders or sensors maybe used to perform this function in alternative embodiments.

Seamer 12 is in operative connection with a force sensor schematicallyindicated 20. The force sensor 20 which is later described in detail,provides signals indicative of the force applied by can forming toolingas it makes the final ironing turn to form a can seam. The force sensoris operable to provide signals during this final forming process foreach can passing through the machine.

Apparatus 10 further includes a can feed sensor 22. Can feed sensor 22is adjacent to an area in which cans enter a station of the seamer. Canfeed sensor 22 enables sensing whether a can has entered this station ofthe seamer. This enables determining if an end should be delivered bythe seamer for placement on a can body in a particular machine station.The feed sensor also enables determining whether data should be gatheredfrom a particular station as its associated cam follower moves acrossthe cam portion in connection with the force sensor as later explained.

Apparatus 10 further includes a can reject sensor 24. Can reject sensoris positioned adjacent to take-away conveyor 16 and is operative tosense cans passing on the take-away conveyor. A can ejector 26 ispositioned adjacent to can reject sensor 24. Can ejector 26 may beselectively operated to divert cans off of the take-away conveyor when afault condition for a can is detected.

Apparatus 10 further includes a monitor apparatus or system generallyindicated 28. Monitor system 28 includes a controller 30. Controller 30preferably includes a processor for executing programmed instructions,as well as at least one data store schematically indicated 32.Controller 30 also has an associated display schematically indicated 34.In the preferred embodiment of the invention display 34 is a touchscreen display which can be used for both input of instructions as wellas output of information. Controller 30 is also in connection with atleast one alarm device schematically indicated 36.

Monitor system 28 preferably further includes a host station 38. Hoststation 38 preferably includes a computer connected to controller 30through a local area network. It should be understood that while onlyone controller connected to host station 38 is shown, a plurality ofcontrollers and seamers may be connected to a single host station. Thehost station preferably includes a screen 40 for display of information.Host station 38 also includes a keyboard 42, mouse 44 or other datainput device. Controller 30 communicates with host station 38 throughARC NET or other suitable field bus network communication scheme.

As schematically indicated in FIG. 1, signals from the force sensor 20,the encoder 18 and sensors 22 and 24 are delivered to the controller 30.The controller 30 is operable to control can ejector 26 and alarm device36 in accordance with the programming of its processor. Further itshould be understood that monitor system 28 in some embodiments may alsobe in operative connection with the motors which drive seamer 12 and/orfeed conveyor 14 and takeaway conveyor 16, to shut them down in theevent of certain fault conditions.

FIG. 2 is a top plan view of a seaming cam 46. Seaming cam 46 is anintegral part of seamer 12 and is used to control the positions of camfollowers which rotate about the seaming cam 46 in engaged relationtherewith. The cam followers which rotate about the cam are inconnection with seam forming tooling. This tooling includes rolls andchucks which form the double seams which engage the can ends to the canbodies.

As shown in FIG. 3, cam 46 includes a first operation track 48. Firstoperation track 48 includes an outward extending lobe 50 as shown inFIG. 2 which engages cam followers which perform a first can seamforming operation. Cam 46 further includes a second operation track 52.Second operation track 52 includes a radially outward projecting lobe54. Outward projecting lobe 54 includes a high dwell portion 56. Camfollowers engaged with the high dwell portion 56 make the final ironingturn which completes the formation of the double seam. As a cam followerpasses over the high dwell portion, cam 46 positions the cam followerwhich in turn moves a seam forming roll which forms the seam between theroll and a seaming chuck. The metal being formed applies a reactionforce which is transmitted by the cam follower to the cam 46. This forceis applied as the can is rotated generally about one and a quarter turnby the chuck, while the cam follower passes over the high dwell portion.The reaction force applied by the cam follower to the high dwell portionis representative of the reaction force of the seam against the seamforming tooling. Variations of this force are indicative of seamconditions which are identified by the apparatus of the presentinvention.

As shown in FIGS. 3, 4 and 5, cam 46 has an inner surface 58. A cut orsaw slit 60 extends radially outward from the inner surface 58 so as topartially separate the high dwell portion 56 from the remainder of thecam body generally indicated 62. Slit 60 enables the high dwell portion56 of the second operation track to be more readily deformable comparedto the remainder of the cam body 62.

As shown in radial cross-section in FIG. 5, the inner surface 58 iscontoured in the area of the high dwell portion to include a first notch64 and a second notch 66 which is angularly disposed from the firstnotch. As shown in FIGS. 4 and 5, each notch 64 and 66 has mountedtherein a pair of strain gages. The strain gages, which areschematically indicated, are R1 and R2 in first notch 64 and R3 and R4in second notch 66, are preferably positioned to extendcircumferentially. The strain gages are positioned to sense deformationof the high dwell portion of the cam in the circumferential direction.While in the preferred form of the invention, conventional foil typestrain gages are used, in other embodiments of the invention othersensors which sense force, or parameters which result therefrom such asstrain, stress or deformation, may be used, including piezoelectricsensors.

As will be understood by those skilled in the art, in the preferred formof the invention the four strain gage resistances are incorporated intoa bridge circuit of the wheatstone bridge type or comparable circuitry.Thus in this manner the resistances are combined to provide anelectrical signal representative of the strain due to deformation of thehigh dwell portion. This is representative of the force of the camfollower on the high dwell portion which is indicative of the reactionforce caused by the can seam formation. In other embodiments otherinstrumentation techniques for measuring force, strain, stress ordeformation may be successfully used depending on the sensor type.

As best shown in FIG. 5, the interior surface of the high dwell portionof the cam also includes a radially enlarged portion 68. Enlargedportion 68 has an opening 70 extending in axial direction therethrough.A reinforcing pin 72 which is slightly smaller in diameter than opening70 extends in the opening. Pin 72 extends from cam body 70 and acrossslit 60 and into opening 70. Pin 72 serves as an extending portion ofthe cam body which acts to limit the extent of deflection or deformationof high dwell portion 56.

As shown in FIG. 5, in operation of the invention a cam follower 74moves across the high dwell portion 56 of the cam 46 in a direction ofarrow D. As the cam follower moves it rotates in engagement with cam 46in a direction of arrow G. The force transmitted by the cam followerfrom the can seam is directed radially inward against cam 46 asindicated by arrow F.

Because the force represented by arrow F is directed radially inwardagainst the relatively deformable high dwell portion of the cam, it ispossible that a malfunction may result in excessive force against thehigh dwell portion. To prevent such excessive force from causing thehigh dwell portion to fracture or permanently deform, extending pin 72serves to engage the wall bounding opening 70 when high dwell portion 56deforms inwardly a maximum safe permissible amount. The engagement ofpin 72 with the wall bounding opening 70 serves to provide additionalstrength to the high dwell portion to prevent it from taking on apermanent inward set or otherwise being damaged due to excessively highforces.

Although not shown in FIGS. 3, 4 and 5, it will be understood by thoseskilled in the art that suitable flexible coating materials or othersealing materials may be applied to the area of the slit 60 and theopening 70 to minimize the infiltration of dirt and other contaminantsinto those areas. The avoidance of such contaminants insures that theseportions are relatively movable and perform their functions in arepeatable manner.

As shown in FIG. 1, controller 30 is in operative connection with thestrain gage resistances which comprise sensor 20. Controller 30 is alsoin operative connection with encoder 18. The encoder provides signalswhich are synchronized with the position of each cam follower 74. It canbe determined that the cam follower associated with a particular stationof the seamer 12 engages the high dwell portion of cam during eachmachine cycle, a certain number of pulses or counts after the pointwhere the encoder gives its “0” or initialization pulse. Likewise, forthe same cam follower, a number of pulses corresponding to the locationwhere the cam follower disengages from the high dwell portion can bedetermined. By programming this information in the monitor system 28,signals from the force sensor 20 which are generated as a particularstation cam follower passes over the high dwell portion, can beidentified as data from that can forming station.

The range of pulses or counts for the cam follower associated with eachmachine station can be readily determined during set-up of theapparatus. This enables sensor data associated with each seaming stationto be identified. This is preferably accomplished during set-up byprogramming this information in the controller 30.

The encoder 18 also preferably produces pulses at the same physicallocation of a cam follower each time the cam follower moves across thecam 46. The apparatus preferably operates to sample the signal from theforce sensor 20 responsive to generation of each encoder pulse. Thisenables the controller 30 to generate signals corresponding to the forceapplied by a cam follower associated with a particular station in anumber of physical locations as the cam follower moves across the highdwell portion. This data which shows how seaming force varies with timeas the cam follower moves across the high dwell portion, is referred toas a can seam profile. By storing this data in the data store 32, thecontroller is enabled to accumulate a large number of sensor readingsfor the same locations associated with a cam follower for a givenstation.

This ability of the apparatus of the present invention to store dataassociated with particular seaming stations, enables establishment of abase line profile for each seaming station. The base line profile isrepresentative of data for a number of good seams formed in oneparticular station. To establish the base line profile, the processor incontroller 30 executes a computer program which preferably includes theprogram steps schematically indicated in the flow chart in FIG. 27.

To establish the base line profile, a set-up person conducting theset-up of the machine, first determines the range of pulses thatcorrespond to the cam follower for the station of interest passingacross the high dwell portion. These can be determined throughcalculation or by observation through movement of the seamer components.For purposes of FIG. 27, the starting pulse of interest is indicated as“X” and the ending pulse is indicated as “N.” Although FIG. 27 shows thecalculation of the base line profile for only a single station, itshould be understood that the controller is preferably used to establishbase line profiles for all the stations simultaneously in a similarmanner. This is done by establishing the encoder count range for thetime in the machine cycle when each of the seamer stations has its camfollower in engagement with the high dwell portion of cam 46.

To establish the base line profile, a plurality of sample cans having“good” seams are gathered. Good seams are identified in a conventionalmanner based on the criteria for the particular type of can being formedin seamer 12. A good can is manually placed in the station of interestin the can seamer, and the seamer is started as indicated by a step 76.As the seamer runs, pulses are received by the controller 30 at a step78, and the pulses are counted from the initialization pulse at a step80. The controller then executes steps 82 and 84 to determine if thepulses generated by the encoder correspond to the location of the camfollower in engagement with high dwell portion for the station ofinterest. If the pulses from the encoder correspond to the range ofinterest (between X and N), the controller 30 operates to sample thesensor signal at each pulse of the encoder at a step 86 and to store thecorresponding data in connection with the pulse number in an array inthe database in a step 88. As indicated in steps 82 and 84, datacorresponding to the pulses outside the station of interest aredisregarded for purposes of calculating the base line profile for thisstation.

Controller 30 is preferably programmed to require a certain number ofdata sets associated with good cans passing through the particularstation in order to calculate the base line profile. Using a largernumber of good cans increases the amount of data on which the base lineprofile is based. For many types of cans at least a dozen good cans maybe used but the actual number may depend on the circumstances. Aftereach good can is run, controller 30 executes a step 90 to determine ifthe number of good cans passed through the station has reached the valueprogrammed for determination of the base line profile. If it has not,the controller 30 prompts entry of a further can at a step 92. Theprompting may be done at display 34 or on screen 40 of the host station38 or both. In response to such prompting the process is repeated withanother good can.

The process of taking data with known good seams passing through thestation is repeated until the predetermined number of data sets isreached. At this point there is an array of data stored in thecontroller. The controller 30 then executes a step 94 to average eachset of sensor readings associated with a particular numbered data pulsein the array. By averaging the set of values associated with each datapulse, a value corresponding to an average force on the cam is obtainedfor a given location of the cam follower as it moves across the highdwell portion. This averaging is done for each set of sampled sensorvalues corresponding to a particular data pulse in storage. Once all thedata has been averaged the controller 30 operates to store in a datastore the base line profile values for the particular station at a step96. The base line profile thus represents the average sensor reading forgood cans at each physical location where an encoder pulse is generatedas the cam follower moves across the high dwell portion. Once the baseline profile for the particular station is stored, the controller 30indicates that the base line data is stored at a step 98.

It should be understood that controller 30 contains additional circuitryfor obtaining readings from the force sensor. In the case of the straingage type sensors discussed, the controller 30 contains appropriatecircuitry for the wheatstone bridge and to amplify the signal. Theamplifier is also combined with a filter to attenuate signals that havefrequencies that are outside the range of interest. Further, the forcesensor is also connected to an analog to digital (A/D) converter, whichconverts the sensor signal to a digital signal. This facilitates storingand processing sensor reading values. The required controller circuitrywill depend on the particular type of force or other sensors used.

In the preferred form of the invention the monitor system is alsocalibrated to provide an indication of the level of force which is beingapplied by the cam followers to the high dwell portion of the cam. Thisis accomplished by applying a known force in generally centered relationon the high dwell portion. This can be done using a hydraulic ram orother suitable device which enables the application of a known appliedforce. In the preferred form of the invention the applied force forcalibration purposes is 453.5 Kg. (1000 pounds). This value is usedbecause it is generally the average level of force applied by the camfollowers in the high dwell portion in an exemplary embodiment. Ofcourse, in other embodiments the normal level of application force maybe determined from the base line profile data.

In the preferred form of the invention the sensor output is calibratedto applied force by varying the known force applied to the high dwellportion of the cam. By obtaining at least two sensor signals for twoknown force levels, the controller 30 is programmed to interpolate andextrapolate from these points to provide an indication of the forcelevel reading. Preferably, several known force readings are appliedduring set-up and the controller executes a programmed routine whichprovides a corresponding force level in kilograms, pounds or other unitsfor a given force acting on the high dwell portion of the cam.

It will be recognized by those skilled in the art that because the highdwell portion of the cam comprises an arcuate range of angularpositions, calibration of a force in kilograms or pounds mustnecessarily be done by applying known forces at only one location.Because the cam follower moves throughout the high dwell portion, thecorresponding output in kilograms or pounds must necessarily be arelative reading and does not represent with absolute accuracy the forceapplied at a particular point away from the location of the calibrationforce. Nonetheless, the ability to express the cam follower force inpounds or other units is very useful.

Once the high dwell portion of the cam has been calibrated, the setupperson sends cans having known undesirable conditions through the seamer12 and observes the levels of cam force encountered. The observation ofthe particular can conditions is facilitated by the controller executingthe program steps which are schematically represented by the flow chartin FIG. 7. FIG. 7 shows the generation of a can seam profile for aparticular station of the seamer through which a can is passing. Fromthe start point 100 the controller receives an encoder pulse at step 102and then determines if the pulse corresponds to the station of interestat a step 104. If the pulse is within the station range the controller30 operates to read or sample the force signal generated from the forcesensor at a step 106. The controller further operates to retrieve thebase line profile data element corresponding to that encoder positionfrom memory in a step 108. The controller then operates to subtract thebase line profile value from the sampled sensor value at a step 110 toproduce a data element. The controller then stores each data element foreach encoder position at a step 112. Then at a step 114 the controllerdetermines if all the values for that station have been read and stored.If all the data elements have been calculated the controller thenexecutes a step 116 to calculate an average of all the data elementvalues for the set associated with that particular can seam.

The execution of this process by the controller 30 provides afundamental advantage of the invention. This advantage is that althoughthe force applied to the high dwell portion 56 of the cam 46 may varysubstantially for the different positions of the cam follower, thesubtraction of the base line profile data generates output data which isgenerally linear if the seam is a good seam. This is graphicallyrepresented in FIGS. 11 and 12. FIG. 11 shows a cross sectional profileof a good double seam generally indicated 118. FIG. 12 shows a screendisplay 120 corresponding to seam 118. In screen display 120 the dataelements derived by the controller for the particular station ofinterest are shown as a jagged line at the center of the screen. Thisline shows that although the data elements vary, the overall layout ofthe data elements is generally linear. This facilitates theidentification of irregular seams electronically much more readily thanwould otherwise be possible because force values from sensor 20 in theirunmodified form are often generally non-linear.

Although the preferred embodiment subtracts the respective base lineprofile from the can seam profile, alternative forms of the inventionmay reduce the base line profile by the can seam profile, or otherwiseanalyze or display the differences between the profiles. The differencebetween the profiles is useful in identifying irregularities.

The ability of monitor system 28 to output data representative a seamprofile as a generally linear function also facilitates theestablishment of a plurality of force levels at which fault and otherconditions are to be indicated. Further, because the output of thesensor and the resulting displays are calibrated in pounds it enablessetting levels for these threshold values in pounds.

In the preferred form of the invention the establishment of suchthreshold values is preferably done by running cans with knownundesirable characteristics through the various stations of the seamerand observing the outputs. Thus, the threshold value at which a tightseam fault should be indicated can be determined experimentally.Determining this is facilitated in the preferred form of the presentinvention because a can having a particular fault condition may be runthrough each of the stations of the seamer and the force levels viewedwith reference to the base line profile that has been calculated forthat particular station. As a result, a “high fault” level can be setwhich is appropriate for all the stations. Similarly the same can bedone to establish a “loose fault” level.

A further fundamental advantage of the invention relative to the priorart is that the present invention enables the establishment ofintermediate threshold values which may not be sufficiently tight orloose so as to constitute a fault condition, but which sufficiently varyfrom the base line profiles so as to warrant review and analysis. Thisenables the observation of trends which may be tending towards a faultcondition. As a result, the operator of the system can correct suchtrends before they result in a fault condition.

FIG. 6 shows a screen display of host station 38 upon which fault andwarning threshold values have been set. Screen display 122 shows a“tight level” alarm or fault condition threshold value set at 471.66 Kg.(displayed as 1040 pounds). Correspondingly a loose level alarm or faultthreshold value is indicated at 435.37 Kg. (960 pounds). A tight levelwarning threshold value is set at 462.58 Kg. (1020 pounds) and a looselevel warning threshold value is set at 444.44 Kg. (980 pounds). Ofcourse it should be understood that these levels are determined for theparticular circumstances by experimentation and set by a set up personat the controller 30 or host station 38.

A computer program executed by the processor in controller 30 includesthe process steps schematically indicated in FIG. 8. The computerprogram is operative to test for a fault condition at a particularmachine station after the controller has executed the portion of theprogram shown in FIG. 7. The program compares the calculated averageforce to the high limit threshold value at a step 124. If the averagecalculated value is below the high limit, the controller then checks todetermine if the value is above the high warning threshold value at astep 126. If not, the controller then checks if the average value isbelow the low limit threshold value at a step 128. If the average valueis not below the low limit, it is then checked to determine if theaverage value is below the low warning threshold value at a step 130. Ifa tight fault is found a tight fault indication is given at a step 132.Likewise if the average value is below the low limit, a loose fault isindicated at a step 134. In response to either of these fault conditionsthe controller operates to set a reject flag at a step 136 as shown inFIG. 10. As later explained, the setting of a reject flag is used by thereject portion to divert defective cans from the takeaway conveyor 16.

Once a reject flag is set, the data concerning the force level is storedalong with the fault indication in the data store 32 at a step 138. Thesystem then waits for the next can at the station at a step 140.

If a tight fault is not found but the value is above the tight warninglimit, the controller 30 then executes a step 142 to give a tightwarning indication. Similarly, if the seam value is in the range where aloose warning is to be given the controller 30 executes a step 144 toprovide the loose warning indication. In either of these conditions thecontroller executes step 138 to store the seam force data as well as thewarning indication in the data store 32 for future retrieval.

A typical example of an undesirable tight can seam is indicated 146 inFIG. 13. Such a tight seam 146 produces a seam profile on screen displayof the host station of the type 148 shown in FIG. 14. As indicated inFIG. 14, the average value of the data elements which comprise the seamprofile for tight seam 146 is above the high level tight alarm limitthreshold value. For this reason controller 30 operates when such a seamis encountered to indicate a tight fault and to set a reject flag asindicated in FIG. 8.

FIG. 15 shows a loose seam generally indicated 150. Loose seam 150 wouldproduce a seam profile shown in screen display 152 at the host station38. Loose seam 150 has an average value for its data elements below thelow limit threshold value and controller 30 operates in accordance withits programming described in FIG. 9 to set a reject flag which wouldeventually result in diversion of the can having this seam.

A further fundamental advantage of the invention is that it can identifyvariations in the force applied to the high dwell portion which arerepresentative of other types of seam defects. Further, the presentinvention distinguishes sensor signal variations associated with actualforce variations from signal variations that may occur due to noise orvibration. The process steps by which controller 30 accomplishes thisthrough its programming is schematically represented with regard to theflow chart shown in FIG. 9.

As shown in FIG. 9, the processor in the controller operates toinitialize a counting routine at a step 154. The counting routine isused to sequentially retrieve and process the data elements for aparticular can passing the high dwell portion. In this example thevariable “x” represents the particular element in the sequence that isbeing processed.

The controller operates to retrieve the first value of x at a step 156.A step 158 is then executed in which the value of x has subtractedtherefrom the average force value previously calculated for the passageof that can over the high dwell portion.

The difference between the particular value of x and the average valueis then compared at a step 160 to a stored high spike value (HSV). Thehigh spike value is a stored value which represents a variation which isconsidered likely to be associated with excess metal either on a toolingchuck or roll, or on a can seam. If the high spike value is exceeded,controller 30 then executes a step 162 to determine if the immediatelypreceding data element also exceeded the high spike value. If so, it islikely that the signal is an actual excessive force indication ratherthan system “noise”. In response to finding two successive data elementsexceeding the high spike value, a metal fault is indicated at a step164. Alternatively, if the preceding data element value is not above thehigh spike value (or there was no preceding value) step 162 returns toexecute a step 166 in which the data element variation from the averageis reviewed to determine if it is less than a low spike value (LSV). Ifso, step 168 is executed to determine if a preceding data element wasalso below the low spike value. If this is the case it is consideredthat a low or broken condition of a can, roll or chuck has been detectedand a broken fault is given at a step 170.

If neither a high spike value nor a low spike value is detected theprocessor is programmed to proceed directly to a step 172 to determineif all the data elements in the seam profile have been checked. If not,the processor increments the counter at a step 174 to retrieve the nextdata element and repeats the process steps.

As shown in FIG. 10, if either a metal fault is given at a step 164 or abroken fault is given at a step 170, a reject flag is set at step 136 inFIG. 10. The seam data and fault condition are then stored in the datastore at a step 138.

It should be understood that while in the flow chart shown in FIG. 9only two contiguous values need to be beyond a high spike or low spikevalue to designate a fault condition, other embodiments may includeprogramming that requires more than two successive data elements toexhibit the condition before a fault is indicated. This portion of thelogic executed by the processor in the controller provides fordiscrimination between fault conditions and short duration sensorreadings beyond the values which can occur due to a variety ofconditions such as vibration or interference.

Referring to a screen display 122 in FIG. 6, the “metal level” whichcorresponds to the high spike value is set at 11.33 Kg. (shown as 25pounds) above the data element average for the particular seam. In FIG.6 the “broken level” which corresponds to the low spike value is set at11.33 Kg. (25 pounds) below the average. Further, as shown in the upperright-hand corner of the screen display the designator “spike length” isset at “2”, indicating that two successive data elements must exhibitthe condition before a fault is indicated. It should be understood ofcourse that these levels can be set at other values which areappropriate for a particular seamer and can being produced.

FIG. 17 shows a can forming chuck 176 having metal on a working surfacethereof. Screen display 178 in FIG. 18 shows a seam profilecorresponding to a seam made with the chuck 176. The seam profileexhibits a dramatic high spike in the area of the extra metal. It shouldbe understood that a can forming roll or a can seam having excess metalabout a portion of its circumference will produce a similar metalindication. It should be noted with respect to FIG. 18 that theprogrammed logic modifies the display so as to indicate the type offault detected. This is true of all faults within the preferred form ofthe monitor system.

The screen display of the host station preferably displays linesrepresentative of the tight limits and tight warnings as well as theloose limits and loose warnings in their fixed relative positions.However, the display also provides lines indicating the average for theparticular seam profile as well as variations from the averagecorresponding to the high and low spike limits. These lines vary withthe average value of the data elements which comprise the seam profile.In the preferred form of the invention each pair of these linescorresponding to threshold values is presented in a different color tofacilitate visual identification of a fault, as well as identificationthrough the fault indicator on the display.

FIG. 19 shows a broken chuck 180. Broken chuck 180 is shown with a gapor break so that a portion of its working surface is missing. Screendisplay 182 shows a corresponding seam profile for a seam made using thebroken chuck 180. Of course as before, the screen display 182 also givesan indication of the fault type as well. As shown in screen display 182the threshold values for limits and warnings remain relatively fixedwhile the seam profile average and high and low spike limits shift withthe particular can seam profile.

It will be understood by those skilled in the art that a seam profilesimilar to that produced by broken chuck 180 will also be produced if aseam forming roll or a can seam has a missing portion about itscircumference. This will result in a low spike corresponding to the areawhere material is missing.

FIG. 21 shows a screen display 184. Screen display 184 is presented onthe screen 40 of the host station 38 when it is desired to view the seamprofiles produced by the last can to pass through each station of theseamer. As previously discussed, in this illustrative embodiment a sixstation seamer is used. However, in other embodiments other numbers ofstations may be used. The host station 38 is programmed to provide eachof the seam profiles in a side by side relationship. This enablescomparing differences between the tooling in each station and helps toidentify potential problems. Further, the programming of the hoststation 38 preferably provides for showing the range of force inkilograms, pounds or other units associated with each seam profile. Theprogramming further provides for the scale of the display to beselectively varied to expand the profile either in the vertical or thehorizontal direction.

As shown in FIG. 1, can feed sensor 22 is positioned adjacent to thearea where can bodies enter an empty station of the seamer 12. Feedsensor 22 is operatively connected to controller 30. Controller 30includes a processor programmed to control the dispense of a can end onto the open end of a can body by an end feed mechanism after the bodyhas entered the seamer. Controller 30 is programmed so that if cansensor 22 does not sense a can entering a station of the seamer adjacentto the sensor, no can end will be dispensed to that station.

The invention is also preferably operable to track the position of thestation in which no can is present. Controller 30 is programmed so thatwhen an empty station reaches the high dwell portion of the cam, datafrom the force sensor 20 is not sampled in response to the encoderpulses. This avoids the gathering of data which would necessarilyindicate a low seaming force due to the absence of a can.

The absence of such a can passing through the encoder also must beaccounted for in the rejection of cans that have been flagged ascontaining defects. This is accomplished in the preferred embodiment bythe controller holding a record queue of cans that are passing throughthe seamer. If a can is not detected by the feed sensor a null indicatoris placed in the queue. When the null indicator reaches the high dwellportion of the cam, sensor readings are not sampled. This is representedgraphically in FIG. 23. Output screen 186 shown in the upper portion ofFIG. 23 is representative of a display produced on display 34 of thecontroller 30. Output screen 186 shows the seam queue in the seamer. The“I” is representative of the station adjacent the feed sensor and thearrow head is indicative of the high dwell portion. The designator “X”represent the presence of the can in a station whereas the designator“−” represents the absence of a can. When a station missing a canreaches the level of the high dwell portion signals from the forcesensor are not gathered or are alternatively disregarded.

The monitor system 28 also includes a reject portion which operates inconnection with the seam queue. The controller 30 operates so that as acan leaves the high dwell portion a designator is added to a rejectqueue. If the can is one for which no fault condition flag has been set,the designator added to the reject queue is a null indicator whichenables the can to pass along the takeaway conveyor 16 to a boxing orpackaging operation.

If however the can leaving the high dwell portion is one for which afault condition has been detected, the setting of the flag causes adefect indicator to be placed in the reject queue. This is representedin display 188 in FIG. 23 which is a screen display for the host station38. In the reject queue good cans are indicated by the designator “−”whereas cans which have been flagged for having fault conditions areindicated by the designator “X”.

In operation, reject can sensor 24 senses each can passing on thetakeaway conveyor 16. If the can passing the can sensor corresponds to a“good can” indicator in the reject queue, the can is allowed to pass andthe can indicator for that can is deleted from the reject queue once thecan passes the sensor without further action. However, if a flaggedfaulty can is indicated at the queue, when can reject sensor 24 sensesthat can traveling on the takeaway conveyor, controller 30 actuates canejector 26. Can ejector 26 is preferably a solenoid actuated gate typecan diverter which pushes the particular can off the takeaway conveyorinto a storage area. Of course, other types of divert mechanisms may beused depending on the circumstances.

It should be noted that a fundamental advantage of this invention isthat even though the cans do not pass on the takeaway conveyor insynchronized relation with the seamer they are nonetheless identifiedand diverted if necessary. This is true even though the seamer may havestations which do not contain cans. This reject portion of theprogramming executed by the processor in controller 30 avoids the needto shut down the seamer to retrieve faulty cans. The seamer may continueto operate while the cans, even though moving at high speed, arediverted. This system avoids the need to identify bad seams after theyhave moved away from the seamer to a location where they are among othercans and the defective can is difficult to identify.

The processor in controller 30 also has in operative connectiontherewith a data store 32 wherein data concerning force levels as wellas totals of cans exhibiting various conditions are stored. Thisinformation may be selectively retrieved at the host station 38 throughits programming to produce a screen display such as screen display 190shown in FIG. 24. Screen display 190 shows data associated with eachstation of the seamer which exhibits characteristics beyond the warningor fault threshold values.

Host station 30 is further programmed to enable providing more detaileddata about the seaming operations in the various stations. FIG. 25 showsa screen display 192 which can be selectively displayed at the hoststation. Screen display 192 includes totals which provide the high, lowand average seaming force for each station, as well as a calculatedstandard deviation value based on a normal distribution. The values ofcans exceeding the various thresholds are also provided. This enablescomparing the performance of the various stations to one another. Suchdata may be useful in determining the need for set-up adjustment ortooling change.

The preferred form of the apparatus of the present invention is alsoprogrammed to provide a record of messages, including seam faults whichhave been determined by the monitor system. This is graphicallydemonstrated in a screen display 194 in FIG. 26. Screen display 194contains a listing of the fault and other messages produced by thesystem, along with the time and seamer station associated with eachmessage. These records include instances of seams exceeding the faultthreshold values previously discussed. As demonstrated with respect toscreen display 194, the messages include not only those associated withlimits and warnings, but also with failures of communication features aswell as indications that set-up parameters have been changed.

It should also be understood that host station 38 may selectivelymonitor parameters associated with several seamers. The operativelyconnected seamer for which data is displayed may be selected using inputdevices such as the mouse 44 or keyboard 42. The particular seamer forwhich data is being viewed is designated by the highlighted seamer iconwhich is shown in the upper portion of the display in the preferredembodiment. For example, in FIG. 25 the data shown is from the seamerdesignated number 2 whereas in FIG. 26 the data shown is from the seamerdesignated number 3. It should be understood that while three seamersare shown, data for more or fewer seamers may be monitored from a singlehost station.

It should be understood that controller 30 in embodiments of theinvention is programmed to actuate alarm devices 36 upon the occurrenceof particular events. Such alarms may be appropriate when it appearsthat consistently bad seams are starting to be produced and immediateattention to the system is required. The alarm devices 36 may be one ormore warning lights as schematically shown, and/or an audible warningsuch as a bell or siren. Such alarm devices may also includetransmission of messages to the host station 38 or to a terminal in aremote location such as a production office.

The set up of the circumstances in which indications of alarm conditionsas well as warning conditions are given using the alarm devices isgraphically represented with respect to FIG. 6. As indicated by thecolumn of icons under “alarms” designated “tight freq”, “loose freq”,“metal freq” and “broken freq”, an alarm is set to be given if twosuccessive cans exhibit one of these fault conditions. An alarmcondition may be given by a red light or siren.

Alternatively, an alarm condition may also cause controller 30 to open arelay contact in connection with a drive motor of the seamer or aconveyor that feeds can bodies to the seamer. Such actions are effectiveto stop seam forming operations when an alarm has been given. Likewiseas shown in FIG. 6, in the column under “warning”, the settings of“tight freq” and “loose freq” indicate that a warning will be given iftwo successive cans indicate either of the warning conditions. Forexample, a warning may be indicated by a flashing yellow lightassociated with the seamer. As warning conditions generally do notrequire seamer shutdown, controller 30 is preferably programmed so theseamer and/or feed conveyor are not automatically shut down in thesecircumstances.

The computer programs executed by the processor within the controller 30to achieve the presentation of the alarms or the warnings is readilyappreciated with regard to the flow charts previously discussed whichare used to identify fault and warning conditions. Because thecontroller is operative to store a record of the fault or warningconditions associated with data for each can, the controller isoperative to check whenever such a condition is indicated to determineif a preceding can exhibited the same fault or warning condition. Whenthe set number of successive seams exhibits the condition, for exampletwo successive tight seams, the warning is given. Alternatively, thesystem may be programmed so that if the number of common fault orwarning conditions which are detected within a set of cans exceedscertain frequencies, a warning is given or a shutdown of seamingoperations is automatically accomplished.

The seam forming apparatus of the invention can be programmed to meetthe requirements of a particular double seaming operation. In situationswhere very tight limits are required, the present invention will enableaccurate set up and maintenance of seam quality. Likewise, in situationswhere a broader range of values can be tolerated, the present inventionenables operation within that range without unnecessary downtime.

Thus, the new double seam forming apparatus of the present inventionachieves the above stated objectives, eliminates difficultiesencountered in the use of prior devices and systems, solves problems andattains the desirable results described herein.

In the foregoing description certain terms have been used for brevity,clarity and understanding, however no unnecessary limitations are to beimplied therefrom because such terms are for descriptive purposes andare intended to be broadly construed. Moreover, the descriptions andillustrations herein are examples and the invention is not limited tothose details shown or described.

In the following claims any feature described as a means for performinga function shall be construed as encompassing any means capable ofperforming the function and shall not be deemed limited to theparticular means described for performing that function in the foregoingdescription.

Having described the features, discoveries and principles of theinvention, the manner in which it is constructed, operated and utilized,the advantages and useful results attained; the new and usefulstructures, devices, elements, arrangements, parts, combinations,systems, methods, equipment, operations and relationships are set forthin the appended claims.

We claim:
 1. A double seam forming apparatus for applying end units to can bodies, comprising: a cam including a seaming track, the track including a sensing portion, wherein a cam follower in operative connection with a can seam moves in engaged relation with the seaming track across the sensing portion; a sensor in operative connection with the cam, wherein the sensor generates a signal responsive to force applied by the cam follower to the sensing portion; and a monitor apparatus in operative connection with the sensor wherein the monitor apparatus is operative to generate a plurality of data elements responsive to the signal as the cam follower moves across the sensing portion, and wherein the monitor apparatus is further operative to generate an average of the plurality of data elements, and to generate an indication signal when at least one data element varies from the average by at least a value.
 2. A double seam forming apparatus for applying end units to can bodies, comprising: a cam including a seaming track, the track including a high dwell portion, wherein a cam follower in operative connection with a seam of a can moves in engaged relation across the high dwell portion; a force sensor in operative connection with the cam wherein the sensor generates a signal responsive to force applied by the cam follower to the cam in the high dwell portion; a monitor apparatus in operative connection with the sensor, wherein the monitor apparatus: is operative to sample the signal at a plurality of locations of the follower as the follower moves across the high dwell portion; is operative to generate data elements responsive to each sampled signal; is operative to average the data elements; is operative to compare the data elements and the average; and is operative to generate a first signal responsive to variation of the data elements from the average by at least a value.
 3. An apparatus according to claim 2 wherein said monitor apparatus is further operative to determine a number of successive data elements varying from the average by at least the value, and wherein the first signal is generated responsive to the number reaching a first limit.
 4. The apparatus according to claim 2 wherein the monitoring apparatus is further operative to reduce each data element by a corresponding base line element for each of the plurality of locations of the cam follower, wherein the base line elements correspond to force applied by the follower in engagement with an acceptable can seam.
 5. The apparatus according to claim 4 wherein each of the base line elements is determined by a process including the steps of placing a known acceptable can seam in operative connection with the cam follower, moving the cam follower across the high dwell portion in engagement with the known acceptable can seam, repeating the process steps with a second plurality of known acceptable can seams, and averaging the second plurality of data elements that correspond to the sampled signals from each of the plurality of locations on the high dwell portion associated with the second plurality of known acceptable can seams.
 6. The apparatus according to claim 2 wherein the monitor apparatus is further operative to store a limit threshold value, and to produce a limit signal responsive to the average of the data elements exceeding the threshold value.
 7. The apparatus according to claim 6 wherein said monitor apparatus further includes a data store including data corresponding to at least one preceding can, and wherein the monitor apparatus is further operative to give a warning signal when the average of the data elements for the can and for the preceding can exceed the threshold value.
 8. The apparatus according to claim 2 wherein the double seam forming apparatus further includes a feed sensor wherein the feed sensor senses the can, and wherein the feed sensor is in operative connection with the monitoring apparatus, and wherein the monitoring apparatus ceases to sample the signal responsive to the feed sensor failing to sense said can.
 9. The apparatus according to claim 2 wherein the seam forming apparatus further comprises: a movable member including a second plurality of stations, wherein cans are positionable in each station, and wherein the movable member moves between a feed position wherein a can is delivered to a station on the member, a sensing position disposed from the feed position, wherein in the sensing position a seam of the can in the station is in operative connection with the cam follower in the high dwell portion, and a discharge position wherein the can is discharged from the movable member; a feed sensor adjacent the feed position wherein the feed sensor generates a signal responsive to a can entering a station at the feed position; an encoder in operative connection with the movable member, wherein the encoder provides a movement signal responsive to movement of the movable member from the feed position to the sensing position; a reject sensor adjacent the discharge position wherein the reject sensor generates a reject sensor signal responsive to sensing a can discharged from the movable member; a can ejector device adjacent the reject sensor wherein the ejector device is operable to selectively divert cans; and wherein the feed sensor, encoder, reject sensor and diverter device are in operative connection with said monitor apparatus, and wherein the monitor apparatus is operable to track a can entering a station of the movable member from the feed position to the sensing station based on the movement signal, to flag as defective the tracked can responsive to the first signal, and to actuate the ejector device to divert the flagged can responsive to the reject sensor signal.
 10. The apparatus according to claim 9 wherein the monitor apparatus is operative to disregard signals from the force sensor when a can is not present in a station at the sensing position.
 11. The apparatus according to claim 2 wherein the cam includes a relatively rigid base portion, and wherein the high dwell portion is more readily deformable relative to the base portion, and wherein the cam includes a reinforcing portion, wherein the reinforcing portion engages the high dwell portion and the base portion responsive to deformation of the high dwell portion.
 12. The apparatus according to claim 11 wherein the cam is generally disc shaped, and wherein the high dwell portion is generally arcuate in diametric cross section, and wherein the cam includes a generally radially extending slit between the base portion and the high dwell portion, and wherein the reinforcing portion extends from the base portion and into an opening in said high dwell portion, and wherein the opening is bounded by a wall, and wherein the reinforcing portion engages the wall upon deformation of the high dwell portion.
 13. A double seam forming apparatus for applying end units to can bodies, comprising: a cam including a seaming track, the track including a sensing portion, wherein a cam follower in operative connection with a can seam on a can moves in engaged relation with the seaming track across the sensing portion; a sensor in operative connection with the cam, wherein the sensor generates a signal responsive to force applied by the cam follower to the sensing portion, and wherein the signal produces a can seam profile as the cam follower moves across the sensing portion in engagement with the can seam; a monitor apparatus in operative connection with the sensor, wherein the monitor apparatus is in operative connection with a data store, and wherein the data store stores data representative of a base line profile, and wherein the monitor apparatus is operative to reduce one of either the can seam profile or the base line profile by the other of the can seam profile or the base line profile.
 14. The apparatus according to claim 13 wherein the monitor apparatus comprises a display and wherein the monitor apparatus is operative to display data corresponding to a difference between the can seam profile and the base line profile.
 15. The apparatus according to claim 13 wherein said base line profile comprises data corresponding to an average of a plurality of other can seam profiles previously generated by the sensor as the cam follower moved across the sensing portion in engagement with such plurality of other cans.
 16. The apparatus according to claim 13 wherein the apparatus comprises a plurality of cam followers, wherein each cam follower is engageable with a separate can, and each can provides a separate can seam profile as the respective cam follower moves across the sensing portion in engagement with the can; and wherein the data store includes a plurality of base line profiles, each of said base line profiles corresponding to one of said cam followers, and wherein the monitor apparatus is operative to reduce each one of either the can seam profile or the base line profile by the other of its respective can seam profile or base line profile.
 17. The apparatus according to claim 13 wherein the signal is sampled by the monitor apparatus at a plurality of locations as the cam follower moves across the sensing portion and wherein the base line profile includes values corresponding to the plurality of locations.
 18. The apparatus according to claim 17 wherein the base line profile is produced by a process comprising the steps of: engaging at least one other can having another seam with the cam follower, moving the cam follower in engagement with the other seam across the sensing portion, sampling the signals at the locations as the cam follower moves across the sensing portion in engagement with the other seam, and storing the sampled signals corresponding to the locations in the data store.
 19. The apparatus according to claim 18 wherein the process further comprises repeating the process steps with at least one additional can and the further step of averaging the stored sampled signals for each location.
 20. A double seam forming apparatus for applying end units to can bodies, comprising: a cam including a seaming track, the track including a sensing portion, wherein a cam follower in operative connection with a can seam on a can moves in engaged relation with the seaming track across the sensing portion; a sensor in operative connection with the cam, wherein the sensor generates a signal responsive to force applied by the cam follower to the sensing portion; a monitor apparatus in operative connection with a data store, wherein the monitor apparatus is operative to sample the signal at a plurality of locations in a sequence as the cam follower moves across the sensing portion, and wherein the data store includes data representative of a limit, and wherein the monitor a apparatus is operative to compare each sampled signal to the limit, and if a first sampled signal is outside the limit, to determine if at least one other sampled signal adjacent to the first signal in the sequence is outside the limit, and if said other signal is outside the limit, to generate a limit signal indicative of an outside limit condition.
 21. The apparatus according to claim 20 and further comprising an input device in operative connection with the monitor apparatus, wherein the input device enables selectively inputting a number representative of adjacent sampled signals in the sequence, and wherein the monitor apparatus is operative to generate the limit signal responsive to the number of adjacent sampled signals in the sequence being outside the limit. 